The present invention relates to conception preventing devices and methods as well as to methods and devices which are of general utility in connection with variable filtering and flow control.
As it is well known, it is possible to prevent conception by interrupting the flow of fluid through the vas deferentia of a male. For example, by way of conventional vasectomies, a part of a vas deferens is removed and the ends of the vas deferens adjacent the removed part thereof are closed. Such vasectomies have the disadvantage of being irreversible for all practical purposes, and therefore it has been proposed to introduce into a vas deferens various types of devices such as valves and the like for enabling a reversible interruption of fluid flow through the vas deferens to be achieved.
However, it has been found that all of the above types of procedures and devices have a serious disadvantage in that highly undesirable results accompany the total interruption in fluid flow through the vas deferens for any substantial period of time. Experience has shown that the fluid which flows through the vas deferens serves not to carry sperm but also to perform other functions such as supplying certain hormones and enzymes to the body, maintaining the lumen of the vas deferens in a open condition enabling fluid to flow properly therethrough, and avoiding undesirable build-up of pressure. Thus, even where a device such as a valve is utilized for reversing the conception-preventing condition, there is an undesirable blockage of flow through the vas deferens. The result is that certain hormones and enzymes fail to be supplied because of the total blockage of fluid flow through the vas deferens. In addition, since there is a total interruption in fluid flow downstream of such a valve or other interruption in the lumen of the vas deferens, there is a tendency for the vas deferens to close upon itself downstream of the location where fluid-flow is blocked. Under these conditions when reversal is desired, as by opening of a previously implanted valve, fluid flow cannot be reliably reestablished through the vas since it may have in the meantime become closed downstream of the location where the fluid flow has been blocked.